Disclosed are intermediate transfer members, and more specifically, intermediate transfer members useful in transferring images such as a developed image in an electrostatographic, for example xerographic, including digital, image on image, and the like, machines or apparatuses and printers, and yet more specifically, printers that generate images of various colors. In embodiments, there are selected intermediate transfer members comprised of an optional supporting substrate such as a polyimide first layer, and a UV (ultraviolet light) curable or UV cured second layer comprised of a conductive component such as carbon black, metal oxides and carbon nanotubes, or mixtures thereof dispersed in an organic inorganic hybrid formed, for example, by the condensation reaction of a bisphenol and a silane containing acrylate, and wherein the polyimide substrate layer when present further includes a conductive component, and wherein the second layer further includes an optional urethane acrylate polymer, a photoinitiator, and an acrylate monomer or a vinyl monomer.
A number of advantages are associated with the intermediate transfer members of the present disclosure in embodiments thereof, such as excellent mechanical characteristics, robustness, consistent, and excellent surface resistivities, excellent image transfer (toner transfer and cleaning), as compared to a number of known intermediate transfer members with a polyimide base layer; acceptable adhesion properties, when there is included in the plural layered intermediate transfer member an adhesive layer; excellent maintained conductivity or resistivity for extended time periods; dimensional stability; ITB (intermediate transfer belt) humidity insensitivity for extended time periods; excellent dispersability in a polymeric solution; low and acceptable surface friction characteristics; and minimum or substantially no peeling or separation of the layers.
More specifically, as UV curing technology matures, the intermediate transfer members illustrated herein provides almost zero VOC volatiles; preparation efficiencies, for example cured within seconds; excellent physical properties such as stain, abrasion, and solvent resistance together with superior toughness, and excellent gloss attainable by numerous coating methods.
Also, as compared to intermediate transfer members that include a number of conductive components, such as carbon black, the dispersed carbon nanotube intermediate transfer members of the present disclosure are UV curable due primarily to the excellent conductivity of the carbon nanotubes; and in embodiments, a small amount, such as 1 weight percent or less, of the carbon nanotubes can be selected to achieve a surface resistivity of, for example, from about 108 to about 1013 ohm/sq for the intermediate transfer members disclosed herein.
Accordingly, in embodiments of the present disclosure, the carbon nanotube containing intermediate transfer members are UV curable when, for example, selected in amounts of about 1 weight percent which allows the UV light to penetrate across the carbon nanotube layer for a complete, almost 100 percent, cure. In comparison, carbon black containing intermediate transfer members usually select a high loading of about 5 weight percent to achieve a comparable resistivity (with less than 5 weight percent, the ITB resistivity may be out of the functional range, for example, over 1014 ohm/sq). Also, a carbon black containing layer substantially prevents UV light from penetrating deep into the layer, thus complete cure is difficult to obtain.
In aspects thereof, the present disclosure relates to a multi layer intermediate transfer member, such as a belt (ITB) comprised of an organic inorganic hybrid, and in embodiments, where the ITB is comprised of an organic inorganic hybrid material, a carbon nanotube surface layer and a polyimide base layer, where the polyimide layer further includes as an optional additive a conductive component, an optional adhesive layer situated therebetween, and which layered member can be prepared by known solution casting methods, and known extrusion molded processes with the optional adhesive layer being generated, and applied by known spray coating and flow coating processes.
In a typical electrostatographic reproducing apparatus, such as xerographic copiers, printers, multifunctional machines, a light image of an original to be copied is recorded in the form of an electrostatic latent image upon a photosensitive member or a photoconductor, and the latent image is subsequently rendered visible by the application of electroscopic thermoplastic resin particles and colorant. Generally, the electrostatic latent image is developed by contacting it with a developer mixture comprised of a dry developer mixture, which usually comprises carrier granules having toner particles adhering triboelectrically thereto, or a liquid developer material, which may include a liquid carrier having toner particles dispersed therein. The developer material is advanced into contact with the electrostatic latent image, and the toner particles are deposited thereon in image configuration. Subsequently, the developed image is transferred to a copy sheet. It is advantageous to transfer the developed image to a coated intermediate transfer web, belt or component, and subsequently, transfer with a high transfer efficiency the developed image from the intermediate transfer member to a permanent substrate. The toner image is subsequently usually fixed or fused upon a support, which may be the photosensitive member itself, or other support sheet such as plain paper.
Intermediate transfer members possess a number of advantages, such as enabling high throughput at modest process speeds; improving registration of the final color toner image in color systems using synchronous development of one or more component colors, and using one or more transfer stations; and increasing the number of substrates that can be selected. However, a disadvantage of using an intermediate transfer member is that a plurality of transfer operations is usually needed allowing for the possibility of charge exchange occurring between toner particles and the transfer member, which ultimately can lead to less than complete toner transfer, resulting in low resolution images on the image receiving substrate, and image deterioration. When the image is in color, the image can additionally suffer from color shifting and color deterioration.
Attempts at controlling the resistivity of intermediate transfer members by, for example, adding conductive fillers, such as ionic additives and/or carbon black to the outer layer, are disclosed in U.S. Pat. No. 6,397,034 which describes the use of fluorinated carbon filler in a polyimide intermediate transfer member layer. However, there can be problems associated with the use of such fillers in that undissolved particles frequently bloom or migrate to the surface of the fluorinated polymer and cause imperfections to the polymer, thereby causing nonuniform resistivity, which in turn causes poor antistatic properties and poor mechanical strength characteristics. Also, ionic additives on the ITB surface may interfere with toner release. Furthermore, bubbles may appear in the polymer, some of which can only be seen with the aid of a microscope, and others of which are large enough to be observed with the naked eye resulting in poor or nonuniform electrical properties, and poor mechanical properties.
In addition, the ionic additives themselves are sensitive to changes in temperature, humidity, and operating time. These sensitivities often limit the resistivity range. For example, the resistivity usually decreases by up to two orders of magnitude or more as the humidity increases from about 20 to 80 percent relative humidity. This effect limits the operational or process latitude.
Moreover, ion transfer can also occur in these systems. The transfer of ions leads to charge exchanges and insufficient transfers, which in turn causes low image resolution and image deterioration, thereby adversely affecting the copy quality. In color systems, additional adverse results include color shifting and color deterioration. Ion transfer also increases the resistivity of the polymer member after repetitive use. This can limit the process and operational latitude, and eventually the ion filled polymer member will be unusable.
Therefore, it is desired to provide an intermediate transfer member with a number of the advantages illustrated herein, inclusive of excellent mechanical, and humidity insensitivity characteristics, permitting high copy quality where developed xerographic images with minimal resolution issues can be obtained. It is also desired to provide a weldable intermediate transfer belt that may not, but could have puzzle cut seams, and instead has a weldable seam, thereby providing a belt that can be manufactured without labor intensive steps, such as manually piecing together the puzzle cut seam with fingers, and without the lengthy high temperature and high humidity conditioning steps. Also, it is desired to generate by environmental acceptable standards intermediate transfer members, thus for example, the intermediate transfer members of the present disclosure can be obtained in the absence of solution casting methods and where solvent evaporation is used.